Using ecosystem-services assessments to determine trade-offs in ecosystem-based management of marine mammals

The goal of ecosystem-based management (EBM) is to support a sustainable and holistic multisectored management approach, and is recognized in a number of international policy frameworks. However, it remains unknown how these goals should be linked to assessments and management plans for marine fauna, such as mammals and fish stocks. It appears particularly challenging to carry out trade-off analyses of various ocean uses without a framework that integrates knowledge of environmental, social, and economic benefits derived from nonstationary marine fauna. We argue this gap can be filled by applying a version of the ecosystem-service approach at the population level of marine fauna. To advance this idea, we used marine mammals as a case study to demonstrate what indicators could operationalize relevant assessments and deliver an evidence base for the presence of ecosystem services and disservices derived from marine mammals. We found indicators covering common ecosystem service categories feasible to apply; examples of indicator data are already available in the literature for several populations. We encourage further exploration of this approach for application to marina fauna and biodiversity management, with the caveat that conceptual tensions related to the use of the ecosystem service concept itself needs to be addressed to ensure acceptance by relevant stakeholders

Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks

Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros) because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR) technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid d/l ratios in eye lens nuclei against growth layer groups in tusks (n=9). Two racemization rates were estimated: one by linear regression (r2=0.98) based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r2 between 0.88 and 0.98). The two estimated 2kAsp values were identical up to two significant figures. The 2k Asp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114−yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (d/l)0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (d/l)0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (d/l)0 and 2kAsp estimates obtained in this study

Habitat preference modelling as a conservation tool: proposals for marine protected areas for cetaceans in southern Spanish waters

1. As part of a project to identify marine protected areas (MPAs) in Spanish Mediterranean waters, habitat preference models were developed using 11 years of survey data to provide predictions of relative density for cetacean species occurring off southern Spain.2. Models for bottlenose, striped and common dolphin described, firstly, probability of occurrence (using GLMs) and, secondly, group size (using linear models) as predicted by habitat type defined by a range of physical and oceanographic covariates. Models for Risso's dolphin, long-finned pilot, sperm and beaked whales used only the first stage because of data limitations.3. Model results were used to define the boundaries of three proposed Special Areas of Conservation (SAC) (under the EU Habitats Directive) and one proposed Specially Protected Area of Mediterranean Importance (SPAMI) (under the Barcelona Convention).4. The study illustrates the value of habitat preference modelling as a tool to help identify potential MPAs. The analyses incorporate environmental data in a spatial prediction that is an improvement over simpler descriptions of animal occurrence. Contiguous areas covering a specified proportion of relative abundance can readily be defined. Areas with apparently good habitat but few observations can be identified for future research or monitoring programmes.5. Models can be refitted as new observations and additional environmental data become available, allowing changes in habitat preference to be investigated and monitoring how well MPAs are likely to be affording protection.6. The study represents an important contribution to the implementation of the Habitats Directive by the Spanish government by providing a robust scientific basis for the definition of SAC and providing results to inform conservation objectives and management plans for these areas. The results identified areas that are important for a number of cetacean species, thus illustrating the potential for MPAs to improve cetaccan conservation generally in the Alboran Sea, a region of great importance for supporting biodiversity and ecological processes in the wider Mediterranean Sea. Copyright (c) 2005 John Wiley &amp; Sons, Ltd.</p